Explanation:
In 185 AD,
Chinese
astronomers recorded the appearance of
a new star in the Nanmen asterism -
a part of the sky identified
with Alpha and Beta Centauri on modern star charts.
The new star was visible for months and is
thought to be the earliest
recorded supernova.
This multiwavelength
composite image from orbiting telescopes of the 21st century,
XMM-Newton and Chandra in X-rays, and Spitzer and WISE in infrared,
shows
RCW 86, understood to be the remnant of that
stellar explosion.
The false-color view
traces interstellar gas heated by the expanding supernova shock wave
at X-ray energies (blue and green) and interstellar dust radiating at
cooler temperatures in infrared light (yellow and red).
An abundance of the element iron and lack of a neutron star or pulsar
in the remnant suggest that the original supernova was Type Ia.
Type Ia
supernovae are thermonuclear explosions that
destroy
a white dwarf star as it accretes material from a companion
in a binary star system.
Shock velocities
measured in
the X-ray emitting shell and infrared dust temperatures indicate that
the remnant is expanding extremely rapidly into a remarkable
low density bubble created before the explosion by the white dwarf system.
Near the plane of our Milky Way Galaxy,
RCW 86 is about 8,200 light-years away and has an estimated radius
of 50 light-years.